An endpoint handles large files or exports. When would you stream instead of loading everything into memory?

When would you stream data instead of loading it all into memory?

Covers large exports, uploads, and API responses where bounded memory matters more than convenience.

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I would stream when the data can be processed or sent in chunks and the full payload does not need to be in memory at once. File uploads, downloads, exports, and large query results are common examples. Streaming keeps memory bounded per request and reduces large allocations. I would still add limits, cancellation handling, and error behavior because streaming does not remove the need for resource control.

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Streaming design, memory bounds, backpressure, cancellation, file and response handling, and operational safety.

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Streaming processes or transfers data in bounded chunks instead of retaining the full payload. It changes API behavior around cancellation, partial progress, timeouts, cleanup, and error reporting, but keeps memory predictable as payload size and concurrency grow.
I would stream when the data can be processed or sent in chunks and the full payload does not need to be in memory at once. File uploads, downloads, exports, and large query results are common examples. Streaming keeps memory bounded per request and reduces large allocations. I would still add limits, cancellation handling, and error behavior because streaming does not remove the need for resource control.
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Loading everything into memory is simpler, but it scales poorly when payload size or concurrency grows. Streaming changes the shape of the work: read a chunk, process or write it, then move on. For downloads I might stream from blob storage to the response; for imports I might parse rows incrementally and batch database writes. The trade-off is more careful handling of partial progress, backpressure, timeouts, cancellation, and cleanup when the client disconnects. I would compare worst-case retained memory and concurrent demand, then keep the buffering that remains explicit and bounded.

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Reading entire files into byte arrays by default.
Ignoring client disconnects and cancellation.
Streaming without size limits or validation.
Holding references to chunks after processing them.

An endpoint handles large files or exports. When would you stream instead of loading everything into memory?

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